Revetment



July 23, 1935.

H. o.l HOFFARD REVETMENT Filed June 29, 19154 Mw/ ///l./

955x? mwwwwww N w Hro/dflorngd @3M M I Patented July 23, 1935 PATENT"OFFICE REVETMENT Harold Hoiard, Tacoma,` Wash., assigner of Yone-fourth to Myrle M."'Williams and onefourth to Alfred Cavanaugh,lboth of Snohomish County, nearArlington, Wash.V

'pplicatiqnimne 29,1934, serial No. 733,074

' 6 claims.`

, My invention relates to. revetments, and to a method.V of revettingbanks against erosion.

y ,A greatdeal of revetment work is being under-v taken in connectionwith iiood control operations,

Because `there are numerous `streams to guard againstand manyfpoints ineach stream where the danger of erosion arises,q'whether. from the banksorfrom dikes, -it is necessary that any revetmentbe simple andinexpensive, It is further ldesirable that itbe of;such character thatin the event itbe-broken or damaged it will be possible to repair and,replacedamaged partsl without undueexpense, loss of time, or ,specialequipment. My invention incorporates allthese advantages, and in:addition provides a simple and inexpensive., method ofplacement,especially to protect the under-,water portions of-banks.

It is; therefore a general object of :theinvention to providea'revetmentand a method of revettingv which has-the'various advantagesspecified and others. Among further advantages are v'that the action ofstream ,flowon the revetment is not permitted by the structure of therevetment to gain access to the banks beneath the revetment. Anotherobject is to provide a revetment which can be formed from elements whichare readilyy made, usually locally, and which can be placed by handlabor.

With these and other advantages in mind, as will appear hereafter, myinvention comprises the novel revetment as a whole and the novel methodof revetting banks, as shown in the accompanying drawing, described inthis specification,` and as will be more particularly defined by theclaims which terminate the same.

In the accompanying drawing I have shown my revetment and the method ofplacing the same in an illustrative form, thereby illustrating theprinciples of my invention.

Figure 1 is a cross section through a stream and bank, showing themethod of placing the revetment. l

Figure 2 is a plan view of the same.

Figure 3 is a detail plan view of adjacent elements of the revetment,showing the manner of securing the same together. Y

Generally speaking, my invention contemplates the employment of a seriesof blocks, preferably of concrete or like material, of a size permittingthem to be handled by a man. These blocks may vary in shape, thoughpreferably, because of the I'functional characteristics and because ofthe cheapness and ease with which they can bey prepared, they are squarein shape. Each block is provided with devices whereby it can be securedto adjacent blocks, so that the whole forms a mat,

' and inthis-mat, and constituting one of the distinguishing features ofmy invention, the blocks are arranged in lines and rows which are placedldiagonally,-that is tosay, at an angle to the direction ofk streamflow, so that when the mat is in place there will not be presented anycontinuous line or space in the mat running in the direction lof, streamiiow. As a result the stream fiow is broken upby small eddys, and thestream tends to silt'in the spaces between blocks rather than'to wash`out material from between them, so that in the course of acomparatively short time the mat becomes in effect a smooth surfaceconsisting of connected diagonally arranged blocks with the intersticessilted in.

It'is valso a distinctivefeatureof myinvention. that a method isprovided whereby the under- Waterfportion of the banks `may be properlypro-` tected by sucha matV forming an integral extension of-,theabovef-waterportion, and thefWhole mat can be constructedconveniently-above thewater, and-,thentneunderfwater portion sunk intoplace.

Referring to the drawing, it will be observed that a number of blocks Iare provided, which, as indicated, are preferably square in shape. Eachof these is provided with securing means, and in this instance eachblock is provided with a pair of crossed rods 2 terminating at one sideof the block in an eye 3, and at the opposite side of the block in a.hook 4. When laid in the mat the eyes on two sides of a block areengaged with the hooks at the adjacent sides of the adjoining blocks,and by bending these hooks over the eyes the blocks are securedtogether. Nevertheless, if a block is broken it can be removed and thehooks bent back suiciently to allow reengagement of new blocks, thusaccomplishing the repair of any broken section of the revetment.

The blocks are placed diagonally, as shown best in Figure 2. They arelaid on the above-water portion of the bank of the stream, as high asmay be necessary to protect the bank, and when a number of these blockshave been thus laid, they will resist any tendency to pull them alongthe bank, although guy ropes or cables may be connected to the hooks oreyes as may be necessary to anchor the mat preliminary. Now a raft 5, orlany suitable float, kmay be moored alongside the bank where the mat hasbeen laid, and this will serve to support an integral extension of themat out over the surface of the water. The outward extension from themargin of the stream will be suicient that when the mat isr permitted tosink it will sink to such extent and extend downward and outward as isnecessary to protect the underwater portion oi the bank. 'I'hus if theunderwater portion be comparatively shallow at one point, the extensionof the mat need not be so great as Where the bank extends to a deeperportion of the bottom of the stream. 1 l

When the extension mat has been laid ongthe raft to an extent suiiicientto protect the underwater portion of the bank the raft is pulled, prefferably in a down-stream direction, from under the mat, and this portionof the mat, consisting of blocks all secured together, sinks as a vrunitand lies along the under-waterlpart of the bank.

This may be continued, the mat being laid'alongy the bank above water,and the extension, being formed integrally therewith and connected tothesunken portion, is laid on the raft, and the raft is progressivelypulled along, sinking the underwater portion of the mat as the workprogresses.

What I claim as my invention isf l g f l 1. A revetrnent comprising apluralityjof slightly spaced blocks and means securing eachY one to alladjoining blocks, to form a ilexible mat, said blocks being so disposed,relative to theY direction of stream ow, that no continuous line betweenadjacent blocks is presented parallel to Vthe stream flow.

2. A revetment comprising a plurality ofv substantially square blocksand means securing each block to but slightly spaced from each adjoiningblock, to form a mat, said blocks being disposed in lines and rowsarranged each at an angle to the direction of stream flow. f Y

3. A flexible revetment mat comprising a plu'-` rality of slightlyspaced blocks arranged in rows disposed angularly with respect to thestream now, whereby the intervening spacesI between the blocks will formno continuous line parallel to the stream flow, and thus no erosion willoccur in such spaces, and means on each block directlyinterengaged withsimilar means on eachadjacent surrounding block to positivelyinterconnect to anchor each block in spaced relation directly to all theadjacent surrounding blocks, thus forming .af flexible, integrate matextending continuously-.over any desired area, and conforming closely'tothe stream bed contour.

-- jThegcornbination of claim 4, in which the blocks are disposedin rowswith their diagonals substantially parallelto the stream flow, thespacing lines running angularly to the stream now, so that no such lineis presented parallel to the stream iiow, whereby the stream action willdeposit silt toI iill the spaces between the blocks,

binding them Y all together into a continuous blanket molded totherprole of the stream bank and bed. Y- I 6. A method of revettingstream banks against erosion which comprises providing elementalconcrete blocks each having a connecting member at each extremity,progressively assembling the mat bymutually interconnecting each lblockin? spaced' 'relation to each adjacentY surrounding block byinterengagement of the connecting members, progressively laying the matas rapidly asv formed upon the stream bank; the rows of blocks beingdisposed so that no continuous line between adjacent rows is parallel tothestream ow, and continuing the assembling and layingvstepsindefinitely to form a single integrate mat of anyv desired extenttransversely of or parallel tothe stream flow, flexing as necessary toconform to irregularities in contour and depth of the stream bankandbed.A l lHAROLD O. HOFFARD.

sof'

